Embodiments of the present invention relate to a pipeline termination skid and a method for subsea connection of a pipeline termination skid to a pipeline end section provided with a pipeline hub.
Development within offshore oil and gas exploration in the recent years has been directed to subsea instalthelations for processing and transport of oil and gas. These subsea installations replace the traditional platforms, where oil and gas are transported up to the platform for further processing and transport. This development of subsea production, processing and transport systems has resulted in an increasing need for subsea connection arrangements for coupling together a longer pipeline installed on the seabed and a so-called spool piece without requiring any assistance of divers. A spool piece is used for connecting a pipeline termination to a pipe termination of a subsea installation, such as e.g. a subsea production manifold. The spool piece is designed to span between the end points of the pipeline termination and the pipe termination in order to complete a connection between the pipeline and the pipe. The spool piece is provided with a spool piece hub which shall mate with a corresponding pipeline hub arranged at the pipeline termination.
A pipeline termination skid to be mounted to a pipeline end section in order to support a pipeline hub of the pipeline end section during and after the connection of the pipeline hub to a corresponding spool piece hub is previously known from WO 2006/005994 A1. This known pipeline termination skid is so designed that a pipeline end section may be mounted thereto subsea by lowering the pipeline end section into a seat of one or more holding units of the pipeline termination skid and thereafter displacing the pipeline termination skid along the pipeline end section so that the respective seat is brought into engagement with an alignment element secured about the pipeline end section so as to thereby fix the pipeline end section axially and radially in relation to the pipeline termination skid. When the pipeline end section has been secured to the pipeline termination skid, a spool piece termination structure carrying the spool piece hub and a clamping device is connectable to the pipeline termination skid by being lowered into engagement therewith. After the landing of the spool piece termination structure on the pipeline termination skid, the actual connection of the pipeline hub to the spool piece hub may be performed by displacing the clamping device and the spool piece hub in relation to the pipeline termination skid and the pipeline hub so as to bring the pipeline hub and the spool piece hub into contact with each other, whereupon the clamping device is activated so as to clamp together the pipeline hub and the spool piece hub. The entire pipeline may be laid on the seabed before the measures of connecting the pipeline to the spool piece are initiated. With this solution, no landing platform or similar structure has to be secured to the pipeline end section when it is descended from the pipe-laying vessel, which will facilitate the pipe-laying operation and allow the pipeline to be laid out by means of a conventional pipe-laying vessel with capabilities related to the pipeline size rather than to a bulky pipeline termination. Thus, this solution will reduce the demands on the pipe-laying vessel with respect to its equipment as compared to other prior art solutions, for instance as disclosed in U.S. Pat. No. 4,019,334 A and U.S. Pat. No. 6,142,708 A, where a landing platform or the similar is secured to the pipeline end section before it leaves the pipe-laying vessel.